Loft conversions
Turn the roof space you already own into a bedroom, bathroom or office.
- Rooflight (Velux)
- Rear dormer
- Hip-to-gable with rear dormer
- Mansard
From £25,000Guide price, fixed after surveySee loft conversions
Loft conversions and extensions, built by one team
Promaester is a construction company working across London and the Midlands. We handle the drawings, the approvals and the build, and hand you the completion certificates at the end.
- No deposit
- Pay weekly for work done
- Build schedule you can check daily
Three ways to get the house you want
Build up into the roof, out into the garden, or put right what you already have. Each page explains the options for your house, what they cost and how long they take.
Extensions
Open up the back of the house for a kitchen-diner, family room or extra bedroom.
- Single-storey rear
- Side return infill
- Wrap-around
- Two-storey rear
From £45,000Guide price, fixed after surveySee extensions
Refurbishments
Renew what you already have: wiring, plumbing, plaster, floors and finishes.
- Cosmetic refresh
- Full refurbishment
- Back to brick
From £15,000Guide price, fixed after surveySee refurbishments
Who you're dealing with
Promaester has been converting lofts, building extensions and refurbishing houses since 2019, on sites across London and the Midlands.
We run our own teams rather than subcontracting the job out, so the people who price your work are the people who build it. Every project is run on a schedule you can see, and signed off by Building Control before we hand it over.
- Registered company no. 12174418, VAT registered
- Four to five of our own trades on site
- Architect and structural engineer arranged if you need them
- Building Control inspections booked and attended by us
Where we work
We work across London and the Midlands, roughly 25 miles out from London and Birmingham. If you’re near the edge of either, call and ask. We’ll tell you honestly whether we can look after your job properly.
London
Birmingham
London
Birmingham
Around 25 miles of London and Birmingham
From first visit to finished room
Five stages. We manage each one and tell you what’s needed from you before it starts.
Survey
We visit, measure, check the structure and tell you what's realistic for your house.
Drawings and calculations
Architect plans and structural calculations, ready for Building Control.
Approvals
Lawful development certificate or planning, Building Control and party wall notices.
Build
Four to five of our own trades on site, Monday to Friday, working to the schedule you can see.
Sign-off
Building Control completion certificate and electrical certificates handed to you.
No deposit. You pay for progress, every Friday.
You never pay ahead of the work. Each Friday you pay for what was built that week, and only if the job has moved forward.
- A live build scheduleShared with you as a Google Sheet and updated daily, including Building Control inspection dates.
- Predictable site hoursMonday to Friday, 8am to 5pm, with a team of four to five on site.
- A considerate siteNo radios and no smoking, at any point in the job.
Recent work
Photos from jobs we've built.
Guides to getting more for your money
Straight answers on cost, planning and layout, written by the team that builds them.
Loft conversions
7 ways to get more loft for your money
Where the money goes in a loft conversion, and the layout decisions that add usable space without adding much cost.
7 min readCosts
What a rear extension really costs in 2026
Why the first metre is the expensive one, what sits outside most quotes, and how to compare builders fairly.
PlanningDo you need planning permission for a loft conversion?
Permitted development in plain English: the volume limits, the front slope rule and when you need a full application.
ExtensionsIs a side return infill worth it on a narrow terrace?
The smallest footprint of any extension, and often the one that changes daily life the most. Here's when it pays.
Questions people ask before booking
Most rooflight and rear dormer conversions are permitted development if the new roof space stays within 40m³ on a terraced house or 50m³ on a semi or detached house, stays below the ridge, and doesn't extend the front slope facing the road. Mansards, flats and houses in conservation areas usually need planning. Every loft conversion needs Building Regulations approval.
A single-storey rear extension can go 3m beyond the original rear wall, or 4m on a detached house, and no more than 4m high. Those limits rise to 6m and 8m if the council grants prior approval, which involves consulting your neighbours. Anything more than one storey is limited to 3m and must stay 7m from the rear boundary.
If your house shares a wall with a neighbour and the work affects it, for example steel beams bearing into the party wall, notice must be served under the Party Wall etc. Act 1996. We'll tell you at the survey whether it applies.
In most cases, yes. Access is from the scaffold for most of the job, and we only open into the house for the new staircase towards the end.
Usually not for the whole build. The new shell goes up outside the existing wall first, and we only break through once it's weathertight. We agree the date for that with you so you can set up a temporary kitchen.
After the survey and drawings you get an itemised quote. Anything you ask to change during the build is priced and agreed before we do it.
Book a survey
We’ll visit, measure up and tell you what’s realistic for your house, along with a guide price for each option worth considering.
Prefer to talk it through?0800 099 6660